


A Perilous Path to Intimacy

by 0neType



Category: Undertale (Video Game)
Genre: Alternate Universe - Human, Alternate Universe - Werewolf, Anal Sex, Banter, Begging, Blow Jobs, Butt Plugs, Crying, Dirty Talk, Established Relationship, Explicit Consent, Flavored Lube, Fluff, Hand Jobs, Humour, Kissing, Knotting, Lube, M/M, Making Out, Mating Cycles/In Heat, Penetrative Sex, Praise Kink, Smut, Werewolves in Heat, slight Nightmare/Ccino
Language: English
Status: Completed
Published: 2020-06-21
Updated: 2020-06-21
Packaged: 2021-03-04 07:41:52
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 8,419
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/24846235
Author URL: https://archiveofourown.org/users/0neType/pseuds/0neType
Summary: Killer is strung out by the effects of heat and Nightmare offers to help him through it.
Relationships: Kight - Relationship, Killer/Nightmare, NightKiller - Relationship
Comments: 9
Kudos: 176





	A Perilous Path to Intimacy

**Author's Note:**

  * Inspired by [A Curious Case of Possession, Ghouls, and How Nightmares Can Come True](https://archiveofourown.org/works/20841770) by [Mutatedbunnies](https://archiveofourown.org/users/Mutatedbunnies/pseuds/Mutatedbunnies). 



> If you've read the fanfic this is inspired by, please note that I've set it to take place _before_ the events in it!
> 
> If you're unfamiliar with it, the good news is that you can read this fic as a werewolf/human heat AU and go in without any other info! Still, if you're like me though, and you like having a little bit of background, here are some things to keep in mind as you read:  
> \- Killer is a werewolf  
> \- Nightmare is a human (with some intuitive magical capabilities but they don't come up in this fic LOL)  
> \- Night is 'uncorrupted' in this  
> \- Nightmare and Killer have known each other since at least 3rd Grade  
> \- Night is dating Killer and is also dating Ccino; they're all aware and consenting of this  
> \- Killer and Ccino's clans forbid them from interacting with or even meeting each other  
> \- Horror and Dust are Killer's roommates  
> \- Horror, Dust and Killer are in a terrible band (this also doesn't come up in the fic despite me trying to fit it in somewhere, but I mention it here anyways because it DELIGHTS me and I'm sad I couldn't bring it up umu)
> 
> And a big thank you to Mew for giving me permission to write this!! 💖

Nightmare gets to his boyfriend’s apartment with a backpack on, a frown on his face, and his cellphone in hand as he types out a quick text.

The door to Killer’s apartment is locked, which is already a bad sign. Usually, by the time the elevator stops at his floor, Killer can smell Nightmare coming. He’d unlock the door and that would let Nightmare walk in at his leisure. As the seconds tick past, however, it becomes clear that today isn’t the usual case. Nightmare continues to stand outside, staring at the scratched up wood and the golden numbers affixed to the front of it with impatience. He waits about a minute longer before he gives a frustrated sigh and reaches out to knock against the hardwood.

It opens up before he gets the chance to.

He’s greeted with the sight of Killer’s haggard face, sleepless and on edge. The circles under his eyes are steadily heading towards looking like bruises. His hair is a mess, sticking up every which way, and his red, flannel shirt is crumpled and slept in. Nightmare’s heart twists in his chest. He tries not to stare.

“Hey,” Killer croaks, “Sorry, I was on the balcony. Left my phone on the table.”

“Balcony? Were you smoking?” Nightmare asks, walking in as Killer steps aside to make room for him to pass.

His question is answered almost immediately by the sight of an empty carton of smokes on the kitchen counter to his left. Nightmare stops in place, looking over his shoulder to level his gaze at Killer. His boyfriend shrugs at him, sheepish.

“You already know it doesn’t affect me the same as humans—”

Nightmare cuts him off, turning back around. “What I protest to is you using it as a crutch.”

There’s a tired chuckle from behind him, which creases Nightmare’s brow and worries him further. Usually, Killer takes every opportunity to tease and argue with him. The fact that he’s just letting it go right now speaks volumes about his state of being.

Heart growing heavier by the moment, Nightmare walks further into the apartment and deposits his backpack on the couch before taking a good look at his surroundings.

As expected, the place is a mess—more so than usual. On a regular day, Killer and his roommates are unorganised, but not exactly filthy. Today, however, there are clothes both on the floor and over the furniture, empty cans of energy drinks on the coffee table and entertainment stand, as well as chip bags and their crumbs spilling into the carpet; utter chaos in the small space.

Nightmare bends to pick up the TV remote from where it’s fallen next to the table. At the same time, he keeps his voice as free of concern as he can.

“Normally you’d know I was coming even _if_ you were out smoking outside.”

“Heh, yeah.” There’s a momentary pause, like Killer has to take a breath before he continues. “But I guess things are a little off from normal, huh?”

Nightmare returns the remote to its regular spot and straightens up again. His heart pounds restlessly in his chest. Beyond the initial glance at Killer’s face when he’d first arrived, he hasn’t really taken in the full of his appearance. He doesn’t know the full extent of how this situation has affected the werewolf.

He braces himself, taking a breath and turning around.

Killer looks… distant.

There’s a glazed quality to his eyes, like he’s watching Nightmare but not really seeing him there. His gaze is hooded, eyelids drooping down like he hasn’t slept in weeks. A faint flush is obvious on the soft of his cheeks and down his neck. It likely continues beyond that, and Nightmare follows it southwards, though he can’t see skin past Killer’s button-down. His eyes come to a rest just below Killer’s waist and Nightmare’s face goes hot at the familiar shape outlined through his jeans.

He snaps his gaze back up. “I’m sorry. I should’ve come over immediately last night when you texted, but I had to pack and I had to wait till morning to let Dream and Ccino know where I’d be.”

“It’s fine, I can take care of this myself. I’ve done it before.” Killer shakes his head. “You don’t have to do this for me, Night.”

‘This’ being helping Killer deal with heat.

While Killer doesn’t experience estrus directly himself, being around his clan during the annual season for it exposes him to the pheromones released by those who do. It does a number on him, and Nightmare is reminded of years previous when he wouldn’t hear back from Killer for an upwards of nine or ten days while he dealt with it on his own. Nightmare’s offered his help before, but Killer has always brushed him off with a laugh.

This year marks the first time Nightmare’s proposal to assist has been hesitantly accepted.

He meets Killer’s gaze directly, firm. “There’s no ‘have to’ about it. I want to.”

His boyfriend’s expression softens, and Nightmare is struck dumb by just how fond he looks.

Killer has a habit of saying he doesn’t care enough; blames it on the werewolf side of himself, but Nightmare knows from experience that it’s false. He’s known Killer for years. He’s been by his side since they were kids passing notes to each other in class, snickering over childish things with not a thought in the world. He knows exactly the way Killer’s eyes light up when he’s excited, knows the way his mouth curls when he’s upset, knows the tightness in the set of his shoulders when he’s angry.

Killer cares more than he gives himself credit for.

He clears his throat in the silence. “Horror and Dust couldn’t tell me how long the effects of heat would last with a partner—said it was different for everyone. So I brought enough extra supplies for a week. I figure you already have some to begin with so we could pool our resources and be set.”

“You’re so thorough,” his boyfriend laughs, low and raspy.

“One of us has to be.”

Killer hums something noncommittal and walks a wide berth around him to get to the back of the couch. Nightmare’s gut twists, knowing that Killer is still keeping his distance like he thinks he’ll infect Nightmare if he gets too close. His boyfriend leans over the couch and plays with the straps on his backpack, looking thoughtful as he opens up a zip.

“By supplies, do you mean like food? Or do you mean—” Killer digs through the bag and freezes. He pulls out a familiar item with a wolfish grin on his face. “Ah, yes. Lube.”

Nightmare blushes. “I brought food too, actually. And a spare change of clothes.”

“Don’t think clothes are really going to be part of the equation to be honest.”

“That’s why I only brought one set.”

Killer laughs again, but the reservation in his posture remains. He fiddles with the tube in his hand, snapping the cap on and off rhythmically. His gaze skirts off to the left as he speaks again, voice gruff and uncertain. “I mean it, Nightmare. If you want to go, you can. At any point, not just right now at the beginning.”

There’s a bristly part of him that wants to roll his eyes and say that he knows what he’s getting into, knows what he _wants_ , and that he’s not going anywhere. But there’s another that knows how hard it is for Killer to be this open at all. Between him, Killer and Ccino, only one of them is any good with being emotionally vulnerable, and it certainly isn’t the two people in this room right now.

So instead he swallows down his immediate response and walks a few careful steps towards his boyfriend. Killer watches him as he does so, gaze locked on him with something fixated and nearly hungry. Once he’s within touching distance, he rests a hand on Killer’s forearm, rubbing circles into it gently with his thumb. His boyfriend shivers.

“Okay,” he says, soft, “I’ll keep that in mind.”

And then Nightmare leans up on his tiptoes and presses his mouth to Killer’s, kissing him slow.

There’s a beat before his boyfriend responds, and then Killer is kissing him back, one arm coming around to hold him steady by the waist. It’s a chaste kiss, but it’s still different from normal. Nightmare can feel the pointed tips of Killer’s canines beneath his lips as he struggles to keep his mouth closed. He can feel the way Killer’s whole body faintly trembles when he’s this close, like it’s taking all his effort to hold himself back.

Nightmare breaks the contact, lowering himself down.

“Have you… gotten off at all yet?”

“Yeah,” Killer swallows, an audible sound in the sudden quiet. “It’s settling in bit by bit. I took care of myself twice since I texted you last night. Tried to get some sleep in between to keep the urge at bay but kept getting woken up feeling heated. I was gonna go a third time but then you said you were coming over so I figured I’d try to smoke it off instead.”

“Did it help?”

Killer laughs, tight. “Not even a little.”

Nightmare glances back down beneath Killer’s waist, fighting the need to look away at the obvious tent in his jeans. It’s not like he hasn’t seen it before—not like he and Killer haven’t been intimate countless times prior to this—but it’s somehow different to know that Killer is under the effects of something primal that’s made him react this way. Something that makes him watch Nightmare with an almost predatory longing, no matter how much he restrains himself.

He uses the hand still on Killer’s forearm to pull him closer, directing him to the other side of the couch. “Sit down.”

The werewolf does as asked, flopping down into the cushions. He winces as he does so and for a moment Nightmare is afraid the heat is starting to pain him. But then, Killer shifts in place and removes a fork from behind him. Nightmare sighs, exasperated, and Killer gives him an apologetic half-shrug as he tosses it to the floor.

“Sorry. Didn’t have much of a chance to clean before you got here.”

“Why’s it even such a mess in the first place?”

“I was restless last night. Thought eating or just like. _Doing_ something would help me work off some energy.” Nightmare purses his lips. It doesn’t seem to have worked since Killer is still obviously keyed up. “Plus, a lot of the mess is from Horror and Dust moving their shit around to keep me from accidentally breaking or fucking it while I’m like this.”

That startles a laugh out of Nightmare.

Killer just looks at him.

He abruptly sobers up. “Oh. You were serious.”

“I’m fine right now… coherent, I mean. Usually, once the heat properly sets in, you can get kind of mindlessly horny.” Killer rubs the back of his neck, awkward. “That’s only on your own, though. It’s supposed to be different with a partner. Having someone else there to help you apparently keeps you more grounded.”

Nightmare lets his words sink in.

It’s quiet, not even the sounds of a car passing on the street outside to distract from the moment.

He made the decision to come here for a reason. He wants to help. Nightmare’s tired of worrying over how Killer must be doing, year after year, without any way to know for himself once Killer goes no-contact during his heats. He doesn’t like how weary his boyfriend looks afterwards. How tired and unsatisfied and exhausted.

“Well,” Nightmare starts, tipping his chin up. “That’s what I’m here for.”

He tugs the lube out of Killer’s hand, taking it into his own. Killer watches him like a bloodhound, all intense focus.

He’s not used to the stretch of silence between them as he drops down beside his boyfriend on the couch. Usually, the werewolf talks a mile a minute when they get intimate, a steady stream of either dirty talk or praise, both of which equally fluster Nightmare. Now though, he barely breathes as Nightmare presses close to his side, near enough to smell the faint spice of cologne left on his shirt.

Nightmare puts the tube down next to him, reaching with his free hand to place it on Killer’s thigh and gently rub it. Killer inhales quick and Nightmare redirects his gaze towards the thick bulge in his pants. He wonders if it’s just his nerves making him imagine it, but he thinks the outline of his cock looks bigger than usual. He reaches over, intent on figuring it out.

Killer catches his wrist.

“Nightmare.”

The low burning fire inside of him stokes higher at the way the werewolf says his name. Nightmare’s heart races just a touch faster. Suddenly, his mouth feels very dry.

“Yeah?”

Killer hesitates, “Are you sure…?”

“Between you and Ccino asking me that over and over, I’m gonna start thinking you don’t actually want me here at all.”

Killer frowns. “Your little kitty wasn’t sure either, huh?”

Nightmare doesn’t answer.

His relationship with Ccino is relatively new compared to the one he shares with Killer, but it’s one that’s been forged with honesty and trust between all three of them. He’d read that heats made were-creatures possessive. He’s not sure if there’s any truth to that, considering Killer and Ccino are normally perfectly fine with sharing him, but he doesn’t want to test any boundaries right now.

Besides, he’s not sure how Killer would take it if he admitted that Ccino was worried that Killer would hurt him. That when he’d told Ccino about his plans, the werecat had expressed immediate concern over the situation. While Ccino also experienced heats of his own, his idea of werewolf heats were far different, imagining them to be a more feral, animalistic thing.

Ccino and Killer have never met each other—aren’t allowed to because of their clans—and the misconceptions they have about each other’s species are unfathomable. Saying something like that might break the tentative peace and good will they have between them, knowing that they each love and care for the same person.

And it’s always been Nightmare’s hope that one day, all three of them will get to be with each other.

No holds barred.

“I’m _fine_ , Killer,” he insists, and this time when he moves his hand, Killer releases his hold.

Relieved, Nightmare reaches out properly, running his fingers along the clothed inside of Killer’s thigh. His boyfriend shivers, the muscles in his leg going tense. Nightmare lets his touch drift, running over the shape of his cock through the denim. He really does feel bigger, both thicker and longer than normal. Nightmare’s heart pounds, wondering at how he’ll be able to take something so much larger than usual.

Killer’s cock twitches under Nightmare’s careful touch, and it’s obvious that Killer’s ready for something far more direct and likely has been for hours before this.

Bolstered by the information, Nightmare reaches up towards the buckle of his boyfriend’s belt. He has a private little laugh at the silver buckle, a wolf’s head sculpted with an intense gaze and sharp, wide teeth. It’s not real silver, of course. He knows from past experiences that the mineral burns Killer’s skin, but it’s just like his dumbass boyfriend to own something tongue-in-cheek like this.

He quickly undoes the belt and pulls Killer’s zipper down. His boyfriend helps his efforts by moving his hips up enough that Nightmare can drag the jeans down past mid-thigh. Then, Nightmare redirects his attention, stroking and rubbing his hand over the jut of Killer’s cock through the thin fabric of his boxers. He continues for a few more passes, till his boyfriend groans, and then he reaches into the gap in his boxers and pulls out his fully hardened dick.

It’s definitely bigger than normal.

The change is subtle, not an overwhelming difference from the usual, but Nightmare finds himself staring anyways. He swallows down a sudden well of saliva in his mouth, eyes fixed on how Killer’s thick cock pulses and throbs in his grip.

“... Nightmare?”

He jolts, embarrassed. “Sorry.”

Killer’s mouth twists in a half-grin, like he’s holding himself back from laughing. Nightmare looks away from it, letting go of Killer and trying to fight back the hitch in his composure by searching for the tube of lubricant.

Once he does, Nightmare squeezes the lube out into his hand, then caps it and puts it aside. Back on track, he takes a breath to steady himself. The gel is cool in his hand and he closes his fist and moves his fingers around to spread it over the full of his palm. When he finally wraps his fingers around Killer’s cock, the werewolf hisses aloud, his dick jumping from the sensitivity.

“It’s… tingly…?” Killer says, questioning.

“That’d be the peppermint.” Nightmare nods at the tube next to him.

“Flavoured, huh. Now why’s that?”

Nightmare rolls his eyes, though despite himself his face still colours. “Why do you think, jackass? I gotta keep myself interested somehow.”

It’s unfair how softly Killer looks at him, smile still on his face, seeing right through Nightmare’s bristly nonchalance. “Funny. I always pegged you as more of a sour apple kinda guy.”

“I brought more than one flavour,” Nightmare says, feigning indifference as Killer’s brows shoot up.

Normally, it’s his boyfriend that brings new things to the table for sex. Nightmare approves or rejects them. But all of this is about making Killer feel good—it’s about taking care of him, and Nightmare is willing to pull out all the stops to do so.

“Now shut up and let me do this.”

Killer chuckles but doesn’t say anything else.

Nightmare refocuses his attention where it should be, readjusting his grip around Killer’s cock. Already there’s precome dripping from the tip, the skin around it angry-hot to the touch. It’s probably been that way for a while and Nightmare can’t imagine how uncomfortable it must feel.

He moves his slicked-up hand from the base of Killer’s cock all the way up to the head in one smooth motion, squeezing gently before he glides down once more. He repeats the action, quick from the get-go as he works his boyfriend over.

“Fuck,” Killer swears, one of his hands reaching into Nightmare’s hair and tugging gently at it.

He knows how much Killer enjoys foreplay and seeing him skip straight to being on the edge of release feels intensely different. It’s a disconcerting switch when he’s used to having to build things up, but it’s necessary when he can see how badly Killer needs to come. Especially when Killer is already biting back sounds like Nightmare’s been edging him for hours.

He changes his grip, making a circle with his pointer and thumb and using only that to stroke instead. He twists his wrist as he jerks Killer’s cock, subtly going faster and faster. There’s more precome to ease the way, far more than there usually is, and Nightmare wonders if this too is due to the heat. He uses it to his advantage, rubbing it all along Killer’s cock and slickening him up alongside the lube, going quicker as he does so.

After so long together, he knows what his boyfriend likes, and he makes sure to run his fingertips along the underside of Killer’s dick with every other upward stroke, adding to the sensation. He keeps at it, tightening the circle of his fingers just under the frenulum and working Killer from base to tip over and over.

“Shit… _shit_ , Nightmare…” Killer moans, breathless.

There’s no point in teasing, not when the werewolf is already so close, and Nightmare changes his pattern one more time, wrapping his whole fist around as much of Killer’s shaft as he can. He squeezes the base and works his cock fast, using his thumb to rub at the area just under the head. Killer’s dick pulses in his grip. He uses his wet thumb to play with the head, teasing at Killer’s slit, pressing down and squeezing the shaft in turn.

And then Killer is coming, eyes clenched shut and a low whine working up out of his throat, like a dog kicked while it’s down. It immediately worries Nightmare, fear that he’s somehow hurt him jumping to the forefront of his thoughts. But as Killer’s release spills down over his hands and his boyfriend opens his eyes, there’s more clarity to them than there was before they started.

“Good?” Nightmare asks anyways, just to be certain.

Killer turns his head, and immediately dips his head down to kiss him. The angle is awkward and Nightmare lets go of Killer’s dick and shifts himself to better face him. The hand in his hair tugs gently and Nightmare moans at the feeling. Killer nips and bites at his lips, licking the rough of his tongue over Nightmare’s mouth in askance and delving in deep when Nightmare opens his mouth to meet him.

When he pulls back, Nightmare is panting, hot all over like he’s the one in heat.

“Yeah.” Killer grins. “Thanks, Night.”

Nightmare flushes, mumbling a quiet ‘don’t mention it’ under breath as he studies his work.

The plan here is to get Killer off a couple times before letting him fuck him. From what he’s read and from what both Killer and Ccino have told him, heat lasts a while, no matter how many times you come in between. It’s fine for them, because their bodies are built to take that strain, but Nightmare is only human. He’s going to need a lot of breaks to keep up.

Case in point, Killer is obviously satisfied, the come all over Nightmare’s hand proves as much, but the fact of the matter is that Killer is still hard. His dick looks the same as it did when Nightmare first pulled it out, albeit more covered in slick and come than before.

“I’m going to blow you,” Nightmare announces.

Killer blinks at him, then starts to laugh. “Why’d you say it like that?”

“Say it like what?”

“I dunno,” Killer continues to chuckle, a side-ways smile curved on his face, canines glinting over his bottom lip, “You just said it weird. Like you’ve got a shopping list of things to do and you’re crossing them off one by one.”

He’s not wrong, and the comparison makes Nightmare blush dark.

“Shut the fuck up,” he bites.

His boyfriend listens, though his chest continues to rumble with laughter for a good few moments afterwards. The smile remains on his face, soft and fond, and Nightmare feels his heart flip-flop at the sight of it.

“Lay down,” he directs, and Killer follows his instructions.

Killer lies back, the armrest tucked underneath his head. He shimmies off his jeans completely, keeping one leg arched up on the couch and the other steadying itself on the ground. Killer is tall and doesn’t even normally fit on the couch, but with the two of them on it like this, it’s an even tighter fit. There’s something intimate about it though, and as Nightmare watches the flush rise in Killer’s face, he finds himself enjoying the squeeze.

He situates himself in between Killer’s spread legs, on his knees as he lowers himself down to his boyfriend’s leaking cock. He takes it in hand, slow and light after the orgasm only minutes ago. While the state of it is just as close to release as it was prior to the handjob, he doesn’t want to risk going too fast and hurting Killer instead.

Nightmare leans over and presses a tiny kiss to the head of Killer’s cock, keeping eye contact with his boyfriend as he does so. The way the werewolf’s eyes glaze is a liquid rush of confidence and Nightmare smirks as he does it again, pressing his lips to the head of his cock and then another to the side just under it.

“Nightmare…” Killer breathes, quiet and wistful.

“Mm,” Nightmare hums, wetting his lips with his tongue before leaving a trail of kisses against the hot skin of his cock from base to tip. “I think I’m enjoying this.”

Killer doesn’t respond, gaze hooded and needy. It’s a heady look that goes straight to his groin, making his half-hard cock twitch. If it were any other time, Nightmare would drag this out, little by little. He’d make Killer beg to fuck his mouth, to hold his head down as he spilled his release down his throat, but it’s not something he can do right now without pushing Killer past his limits.

He files the idea away for another time, instead picking up the lube again and squirting another handful into his palm.

Nightmare slicks Killer up with it, the light scent of peppermint drifting up towards him. Killer makes a noise as Nightmare strokes it over the full length of his cock, something desperate and choked off. He grins at his boyfriend, wide and approving, before he drops down and wraps his lips around Killer’s head.

“ _Fuck_ , Night,” Killer groans as Nightmare sucks on him, tilting his head back, his hands gripping into the cushions to the side and beneath him.

Nightmare wraps his fingers around the base of Killer’s cock, squeezing firmly and enjoying the way his dick throbs in his mouth. The salty taste of precome is easily hidden by the hint of peppermint. Killer was right when he said it tingled, and Nightmare appreciates the pleasant sensation as he takes more of the werewolf’s cock into his mouth.

He uses the tip of his tongue to rub the sensitive area underneath the head, as well as to dip in near Killer’s slit again, tasting him anew. Each motion has Killer tensing and untensing the muscles in his thighs, trying to ground himself. His knees are trembling already, shaking and bending inwards like he can hide himself away. Nightmare bobs his head, going down as far as he can without gagging.

“God, your mouth feels so fuckin’ good.”

Nightmare hums, pleased, and Killer swears aloud at the vibration.

With his free hand, Nightmare cups Killer’s balls, stroking the soft skin gently and massaging with his fingers. He can hear the way his boyfriend’s breath hitches at that and repeats the motion, this time paying particular attention to the sensitive area right in the middle. Killer’s body stiffens and Nightmare swirls his tongue over the head of his cock, keeping the sensations going.

“Hell, Nightmare,” Killer gasps, “God damn, you’re _perfect_.”

The praise makes his face heat further, his own dick twitching in his pants. He spreads his knees a little and ups the pace, dropping his head down as far as he can take the length of Killer’s cock. He hollows out his cheeks and sucks while dragging back up, making sure to keep the rough flat of his tongue rubbing along the bottom. Killer makes a noise like he’s begging, a slurred mess of words escaping him in half-pleas.

Nightmare’s never been able to take Killer properly into his throat without gagging, but he’s found a work-around that gets his boyfriend off with just the same feeling.

He pulls back off Killer’s cock with a wet pop and then flattens his tongue to the roof of his mouth. He takes Killer back in and sucks, bobbing forward and letting him press against the barrier made by the underside of his tongue. As he does so, he continues to stroke and tease his balls, tugging gently on them the way he knows Killer likes.

The stimulation is more than enough and, on the next stroke of the hand on his shaft, Killer grunts and starts to come. Nightmare catches his release directly in his mouth. The salt mixes with the mint of the lube and dribbles down his chin. There’s a lot of it, much more than usual. It’s unmistakable now when there’s no way for him to swallow all of it at once.

Nightmare pulls back. He gently presses a couple more kisses to Killer’s dick, wet and messy, then releases it from his grasp. Just like before, the werewolf is still hard, though it’s not nearly as aggravated looking as earlier.

“You alright?” Killer pants, strained.

Nightmare raises a brow at him, wiping his mouth on his sleeve. “I feel like I should be asking you that instead.”

“Oh, I’m fine.” Killer grins, and he slowly gets up, sitting down half-crossed. A hand drifts up to cup the side of Nightmare’s face, wiping away some lingering wetness with a thumb. “You took a lot though.”

There’s a heaviness to his voice, a low timber that makes Nightmare that much harder.

“I’m alright,” he says, rough.

Killer’s eyes drift down between Nightmare’s legs and look pointedly at the telling bulge there.

“Seems like you need a little help though.”

He doesn’t deny it, tilting his head to kiss Killer’s palm. He keeps eye contact, hooded. “Yeah.”

When Killer kisses him, it feels like drowning. His boyfriend licks into him with a growl, pressing him down until his back hits the couch. Their tongues entwine over and over, Killer sucking and biting without pause. Nightmare can’t breathe, doesn’t want to when it would mean stopping the contact. The werewolf nips at his mouth until his lips are kiss-swollen and Nightmare is moaning desperately. His hips buck, his cock pressing into Killer’s hard stomach.

“I’m gonna fuck you until you’re begging,” Killer promises as he breaks the kiss, says it all in one hot breath.

Nightmare barely hears him, wanting to be kissed again, touched where he aches. He just nods, pressing his lips to Killer’s neck and jaw and mouth all in quick succession. His boyfriend responds by rutting against him, and Nightmare moans aloud when their cocks press up against each other.

He’s content to continue just like this, but Killer pulls away. Nightmare is about to voice his displeasure when his boyfriend stands and tugs Nightmare up with him, pulling him straight into his arms. He yelps, arms and legs automatically wrapping around the werewolf to keep himself from falling.

“Killer, what the hell—!”

He’s silenced with another deep kiss, Killer holding his head with the hand that’s not supporting his weight, rubbing his thumb encouragingly at the back of his neck as he licks into him.

It’s ridiculous how hot it is as Killer carries him from the living room to his bedroom, all without stumbling once. Killer’s powerful arms brace under his ass and against his back, kicking open the door and letting it bounce against the wall. Nightmare keeps his legs wrapped tight around Killer’s waist, moaning into another open-mouthed kiss and rutting his constrained erection into the hard, flat of his stomach. It feels perfect.

When Killer drops him down onto the bed on his back, Nightmare breaks from the kiss with a gasp. He watches, dumbstruck as his boyfriend pulls his shirt over his head, exposing inches of soft skin for him to touch. It’s only when Killer starts to tug off his boxers that Nightmare is reminded of his own state of dress and quickly works to maneuver his own clothing off.

He’s just about to divest himself of his underwear when Killer leans over him, grabbing his wrists and pinning them down to either side of his head.

Flustered, Nightmare glares at him. “What?”

Killer grins, canines sharp and smile even sharper. “Let me.”

Before Nightmare can protest, Killer presses a wet kiss to his mouth, swiping his tongue across his lips and then sucking on the bottom one. Nightmare can’t help the way he moans, hips moving of their own accord as he tries to grind up into the pressure. Killer’s toys with his lip in between his teeth, pulling before letting it go. He’s not nearly done though, and Nightmare shivers as Killer trails his hot, wet kisses along the line of his jaw and then down his neck.

“Killer,” he says, a note of desperation creeping into his voice.

After so long being the one at the forefront of touching, being unable to get his hands on his boyfriend makes him feel bereft. He wants to reach out and hold onto him, wants to twist his fingers up in Killer’s hair. It’s maddening to be held down, but he can’t deny that it makes him harder, cock swelling in the confines of what he’s wearing.

“You’ve been so good to me,” Killer purrs, licking and sucking along his collarbone. “Let me treat you right. I want to get you hot all over.”

“Asshole,” Nightmare manages to groan.

“We’ll get there,” he promises and Nightmare feels his face flush three shades darker.

Killer laughs and resumes kissing his way down Nightmare’s body. He stops at his nipples, looking up at him with a heated glace before swirling his tongue around one and sucking. Nightmare bites back a shout, squirming and shaking as Killer gives the other the same attention, kissing and nipping and sucking before he moves on.

By the time the werewolf reaches the curve of his belly, Nightmare is leaking precome through his boxer shorts, a dark patch at the front of the fabric. Killer raises a brow at him and Nightmare glares, which only makes him beam. His boyfriend kisses his way down the dark trail of hair underneath his navel and then over the top of his undergarments, finally stopping at his erection.

When Killer mouths over the hard sharp of it, Nightmare grits his teeth to hold back a moan. His wrists twist in Killer’s hold, his hips darting up yet again into that welcome pressure.

Killer chuckles, pressing an agonisingly light kiss to the clothed curve of his cock. “Eager, huh?”

“Get me the fuck naked already,” Nightmare demands.

The line of his shoulders shake with more laughter, but Killer obliges. He keeps his eyes locked with Nightmare’s as he takes the edge of his elastic waistband between his teeth and starts to tug them down. He uses his hand to help, and Nightmare swallows dry as his boyfriend easily strips him of the last of his clothes, leaving him entirely bare.

His cock bobs up as soon as it has the space and Nightmare stutters through a breath as Killer’s hot mouth ghosts just past it.

“Hey there,” Killer smirks, pressing a kiss to his hip.

It’s obvious that the werewolf is starting to heat up again. Nightmare can tell from the way his skin feels flushed where they’re touching and in the dilation of his pupils.

“Hey,” Nightmare says, giving Killer a smile of his own, “What’s a guy like you doing in a place like this?”

Killer laughs, delighted, and Nightmare’s heart flutters stupidly in his chest, all affection and soft fondness.

“Oh, you know…” Killer leans in to press a kiss to his lips, quick, his thumbs rubbing circles into Nightmare’s wrists where he still has him pinned. Slow and careful, he releases his grasp, stroking his way down Nightmare’s arms till he reaches his shoulders and rests there. “Just fucking my boyfriend.”

And then he flips Nightmare around onto his stomach in one fluid motion. Nightmare bounces on the mattress, surprised as he’s turned in an instant. Killer snickers, and it sounds like he’s about to say something when his voice chokes off into silence.

Nightmare blushes hotter, having a good idea of what would make him react like that.

“Night,” Killer says, quiet and breathless. His hands trace up the backs of his thighs, pushing them gently apart. His fingers trail over the curve of his ass. It’s very nearly reverent when Killer uses his thumbs to spread him open. “What’s this?”

He could say something sarcastic. He could roll his eyes and tell him it’s obviously a plug, what else could it be? But the careful way Killer holds him, makes him rethink his words.

Instead, he hides his face in the mattress, mumbling, “You mentioned that you sometimes got… bigger than usual during heat. I wanted to be sure I was prepared for you. Besides—you’re always so fucking impulsive, I didn’t want to get hurt if you just plunged in.”

He wouldn’t, Nightmare knows, but it feels like saving face to say so. Even after all these years together, it makes him feel awkward to admit that it’s because he cares. That he doesn’t want Killer to worry about him in a situation where he’s barely holding himself together. Nightmare can handle it all.

There’s a long pause, a moment of total silence as Killer considers his words.

And then.

“I love you, Nightmare.”

His whole face feels like it’s on fire.

“I… I love you too, idiot.”

He’s shying away from what else Killer might say, but breathes in relief when he feels his boyfriend lean down over him. Killer kisses the back of his neck and then the soft skin where it meets his shoulder. Nightmare shivers. The feeling of Killer behind him never gets old, the hard line of his body a welcome comfort.

It feels good to have his weight on top of him; feels good to be held down and pinned. When Killer kisses the top of his spine and starts to make his way down it, Nightmare’s cock aches from the feathery soft touches, so far from where he needs them. He subtly ruts against the sheets, but the friction is nowhere near enough.

By the time Killer reaches the small of his back, nipping and licking the skin there, Nightmare is a trembling mess, heart racing and breaths short. His senses fire all at once, high on alert, when Killer reaches down between them, gripping the plug inside of him from the base. He rocks it back and forth slowly and Nightmare jolts, twitchy as it glances the sensitive spot inside of him.

“Want me to take this out?” Killer asks, a rough, wanting quality to his voice.

“Yes,” Nightmare whispers, barely able to speak at all.

“It’ll leave you empty,” Killer muses, still working the plug in circles, bumping again and again into his prostate, “We can’t have that, now can we?”

Nightmare shakes his head, body starting to tense. His cock pulses, precome steadily dripping down into the sheets beneath him.

And then suddenly Killer is whispering into his ear, body pressed close to him. Nightmare can feel his hardness against the cleft of his ass, can feel the warmth of his skin rubbing on top of his. It’s enough to make his throat tight, longing coursing through him.

“What do you think we should replace it with?”

“ _Please_ , Killer,” Nightmare begs, still quiet.

“Come on, Night. Tell me what you want.”

“Fuck me,” Nightmare pleads, “Fill me up with your cock.”

Killer kisses the side of his neck like a reward, rubbing his cock promisingly against his ass before he withdraws entirely.

Belatedly, Nightmare remembers that they left the backpack in the living room. There’s a wave of frustration as he interprets Killer’s moving back as him leaving to retrieve it from there. He’s about to turn around to check, when he hears the sound of Killer’s drawer opening and relaxes. Sure enough, it’s followed by the familiar snap of a lid and then Killer returns to his place.

The noises behind him are wet and filthy as Killer slicks himself up. They get even louder as his boyfriend comes close, gripping the base of the plug again and slowly easing it out. Nightmare grips tight to the sheets, asshole clenching over the emptiness after hours of being full. His rim feels sensitive, and as Killer rubs a lubed up finger along the outer edge of it, he groans.

“Shh, baby, I’ve got you.”

Although Nightmare already prepped himself before coming here, Killer squeezes out more lube and quickly slides two fingers into his gaping hole. Nightmare gasps, rocking back into the sensation. Killer fingers him quick, scissoring and curving his fingers to rub light and teasing against the firm press of his prostate.

“Killer,” Nightmare keens, “Hurry.”

He does, laying down next to Nightmare in bed. When Nightmare voices his confusion, Killer turns him on his side and adjusts until they’re spooning. He rests his head in the curve of Nightmare’s neck, leaving a soft kiss against his skin as his slick hand cups and kneads his ass. The lube is cool against his flushed skin, and Nightmare shivers at the contact.

“Ready?” Killer asks, and his voice is strained, like the heat is back in full force. From the way his cock throbs behind him, Nightmare is sure there’s some truth to the thought. His own dick aches and he lowers a hand down to give himself some relief, stroking it as he nods to Killer.

“Yeah.”

Killer pushes the head of his cock into him at last and Nightmare gasps at the sensation. The glide is easy, but the stretch is still more than he’s used to. He’d suspected as much from having Killer in his hand and his mouth earlier, but the heat has definitely made him bigger than normal. Nightmare’s heart pounds, senses flaring as Killer breeches him.

His hole clenches tight around Killer’s cock, the nerves around his rim tingling pleasurably. It’s even better when Killer runs his still-wet thumb around where they’re connected, shallowly fucking into him a few times and heightening the sensation. He feels incredibly sensitive, a combination of ignoring his own need this whole time and just from the new stretch, being speared open on something much larger than he’s used to.

He knows he’s not going to last much longer.

“I’m going to move,” Killer whispers against his skin, words slurring together, “Tell me if it’s too much.”

Nightmare barely manages to nod, hot and flushed and oversensitive. He wants, with overwhelming intensity. He wonders if this is what heat must feel like for Killer—if it’s actually infected him as well. It must’ve, because his throat is tight with desire as Killer finally starts rocking back and forth in earnest.

It’s still shallow, barely inches into him, but Killer quickly builds a rhythm up, grinding the head of his cock just scant millimetres above his prostate. The indirect stimulation is unbearable and Nightmare fists his cock and squeezes his eyes shut, pushing his ass further back onto his boyfriend. Killer keeps him steady, a slick hand on his hip as he ruts inside.

“You’re so fuckin’ hot like this, Night.”

He groans, Killer shifting so that his cock is positioned in just the right place, glancing over the sensitive spot inside of him with every pass.

“You look so god damn gorgeous spread open around me, taking my dick so easily.”

It feels so good, it chokes Nightmare up, tears of frustration lining his vision.

“You were made for me Nightmare,” Killer growls into his ear, taking the lobe between his teeth, toying with it. “And I’m gonna make sure to keep you. Make you mine. Fuck you over and over until you’re screaming.”

“Killer.” Nightmare is so desperate to come, it feels like a whole body ache that throbs and wants. “Killer, please.”

“Tell me what you want, sweetheart.”

“Take me, use me,” Nightmare begs, heart pounding so loud he can hear it in his ears. “Faster—harder—anything, fuck Killer, _please_ , I need—”

His boyfriend grips tight to his hips, fingertips near bruising and slams all the way in. Nightmare gasps, voice catching on a broken moan as Killer withdraws then pushes in again. Tears spill down over his face as Killer resumes his earlier shallow thrusting, grinding against his prostate continuously. The pressure builds and Nightmare twists in the sheets, pushing back over and over.

Killer keeps at it, a steady stream of filthy words in his ear while his cock kneads his sensitivity without pause. Warmth spreads over Nightmare’s entire body, his stomach goes taut, his breathing short. His fists grip into the sheets, the hand around his cock stroking and teasing and so _very close_. And then Killer fucks him so perfectly that the line of tension finally breaks and Nightmare is overtaken, wave after wave of pleasure cascading through him.

He’s hardly aware of Killer praising him, too focused on the intense satisfaction as he comes from deep within his body. He feels floaty and light and good, unfocused as he’s moved back onto his stomach and then pulled up to his knees.

His ass is still flush against Killer’s front, and the werewolf continues to pound into him. Deeper this time, fully buried inside of him as he slams in over and over. Nightmare can feel the way Killer’s cock swells inside of him and he moans, hiding his face in the sheets.

“Fuck Night, I’m gonna come,” Killer says, guttural, “I’m gonna fill you up—you want that?”

He nods, lightheaded, “Yeah.”

The high of orgasm finally starts to dissipate and Nightmare feels sensitive all over. But Killer hasn’t come yet and that’s—that’s the whole _point_.

So he arches a little more, makes sure to move back into every thrust, and focuses on the oversensitivity that lets him feel every tingle and ache. His own come is rapidly cooling on his stomach, but his dick makes another valiant effort at hardening again, twitching beneath him.

It’s then that he feels Killer swell a little more, the base of his cock growing hot and firm. The feeling is unlike any other, and Nightmare’s eyes widen as he realises what’s happening.

“Killer, are you—”

“Gonna knot you,” Killer confirms, just barely clinging to coherence, “It’s—I think I—I’ve never—”

He falters with his words, hands on Nightmare’s hips flexing and holding tight. He speeds up, rutting into him faster and deeper.

This too is something Nightmare prepared for, just in case, but he’s still shocked by exactly how big Killer feels inside of him, growing and swelling at the base. The knot catches along his sensitive rim, the sensation too quick, too intense, after his recent orgasm. Nightmare whimpers, fresh tears in his vision.

“Killer,” he whines.

“Shh, I know,” Killer says, voice tight.

The knot grows impossibly bigger and Killer pushes the whole of it into him, making Nightmare shout. His hole clenches desperately and Killer's cock throbs deep inside. The hard curve of his knot presses directly into Nightmare’s tender prostate, rubbing and grinding at it as Killer pounds into him. Nightmare is beyond oversensitive, the sensation making him twist and shake ceaselessly underneath his boyfriend.

“It’s so much,” Nightmare hiccoughs on a sob, tears spilling over his cheeks. “Killer, it’s so much, I can’t—”

“I know, baby, I know. I’m sorry, shh,” Killer whispers, caressing the sides of his waist even as he continues to fuck him hard. He dips down to kiss the small of Nightmare’s back. “You’re doing so well, Night. Just a little more, okay? I know you can take it.”

Nightmare cries out and Killer’s cock pulses within him, the knot tirelessly pressing into his prostate. Despite himself, the discomfort and sensitivity wind right back around into pleasure, his whole body feeling electric. Neither of them speak any further, Killer slamming into him in earnest, fucking him fast as Nightmare gasps and keens and moans.

In the final few thrusts, Nightmare comes again, dry, feeling dizzy and hot with the force of it. And then Killer is coming too, thick spurts inside of him, groaning with relief. His knot stays firm, keeping them locked together as the werewolf continues to spill into him. Nightmare distantly notes that there’s far more come than usual, Killer’s cock twitching and pulsing deep inside.

“Mhnn…” he sighs, entirely worn out.

Killer keeps careful hold of him as he lowers himself down. The knot feels uncomfortably tight inside him, larger than the plug had been. It takes a bit of maneuvering for the two of them to find a decent position to rest in, Nightmare twisting and Killer helping till they’re both face-to-face.

Nightmare leans into his boyfriend’s chest, pressed close as Killer runs his fingers through his hair. He makes a noise, sleepy-satisfied, and the werewolf presses a kiss to his forehead.

“Thanks,” Killer says, and Nightmare takes pride in the fact that he looks much better now.

Gone are the bruises under his eyes and that perpetually tired gauntness to his face. Killer looks tired, but in that well-fucked sort of way that Nightmare always enjoys seeing. It’s clear that he’s actually managed to help.

Nightmare presses a kiss to his collarbone in lieu of an answer. “So. How long will we be stuck like this?”

“Uhh…” Killer thinks, his eyes crinkling up in that way that Nightmare loves. “To be honest, I don’t know. It varies. I’ve never knotted anyone before, but I’ve heard it can range from a couple minutes all the way up to almost an hour.”

“An _hour_?!”

Killer laughs, “We could take a nap?”

“Ugh, we’re going to be covered in dry, crusty come when we wake up,” he grumbles.

His boyfriend grins and leans in for a kiss. Nightmare meets him, their lips warm and soft against each other. Killer pulls back with a tender expression that says far more than the werewolf ever thinks it does.

“Can’t think of a better person to be filthy with.”

Nightmare snorts.

He loves him.

“Yeah, alright asshole.” Nightmare rolls his eyes, patting at the side of Killer’s face. “Let’s get some rest. Who knows how horny you’ll be when you wake up again. We might as well use the opportunity to wind down while we have it.”

“Whatever you say, boss,” Killer teases and Nightmare glares, face heating in embarrassment at the title.

It makes his boyfriend snicker and Nightmare sighs, exasperated, as Killer wraps his arms around him. When the werewolf settles, he’s humming under breath, content. His eyes flutter shut, his breath evening out.

Nightmare takes a good, long, look at his best friend. Every childhood memory, every argument, every confession; he can read it all in the soft curves of Killer’s face. With a smile on his face, Nightmare presses in close.

He lets the rhythm of Killer’s heartbeat lull him to sleep.

**Author's Note:**

> EYYY, IT'S MY BIRTHDAY!! 🎉 I wrote this as a bit of a treat to myself since I'd been meaning to get to it for ages hehehe I hope if you've made it this far, you've enjoyed reading it and use it as a way to celebrate with me! 😌👏✨ As always, thank you!!


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